Photoinduced Selective Synthesis Of Polyfluorinated Compounds Promoted By Trivalent Phosphin

As an important structural unit in the field of organic synthesis,fluorine-containing compounds have a wide range of uses in the fields of organic materials,agricultural chemicals and pharmaceuticals due to their unique biological activities.Moreover fluorine-containing compounds are also an important class of synthons,on the synthons,a series of skeleton structures containing different functional groups can be rapidly constructed through various transformation and derivatization operations.Although the continuous efforts of scientific researchers,many methods for constructing fluorine-containing compounds have been established.However,most of the synthesis methods requires the transition metals,which makes a certain amount of metals remain in the reaction system,there are some disadvantages in metal compounds,such as harsh synthesis conditions,high prices and troublesome post-processing,which further limits the transition metals in the applications in organic synthesis.Therefore,the development and the use of new synthetic methods can improve the economics of chemical synthesis and can effectively reduce the harm to the environment.The rapid and efficient synthesis of fluorine-containing compounds still remain certain challenges.Phosphine catalysis is a significant research area developed in the field of organic catalysis in recent years.This catalytic method can realize the addition reaction of olefin compounds with other electrophiles,and efficiently synthesize of the compounds frameworks cannot be constructed by traditional methods.In addition,phosphine catalysis has the advantages of simple operation,mild reaction conditions and environmental friendliness This method can solve the problems existing in transition metal catalysis.We successfully realized the 1,5-addition reaction of cyclopropylalkene and perfluoroiodoalkane catalyzed by trivalent phosphine,constructed a series of polyfluorinated compounds containing perfluoroalkyl group in one step,the model reaction pathways and functional group transformations were studied.The specific research is as follows:Analyzing the feasibility of trivalent phosphine-mediated radical reaction of cyclopropyl alkenes,we designed a photo-initiated trivalent phosphine for the1,5-addition of perfluoroiodoalkanes to cyclopropyl alkenes reaction.Through the screening of the light source,trivalent phosphine reagent,solvent and reaction time,the optimal reaction conditions were found as follows:using blue light as the light source,P₂ as the trivalent phosphine reagent,and reacting in acetonitrile solvent for 3h.The target product can be obtained with 13:1（E/Z）regioselectivity and 96%yield.Finally,the optimal conditions of the model reaction were taken substrate scope expansions were carried out.A series of novel target compounds containing polyfluorides were constructed in a fast,efficient and concise manner without the transition metals.Based on this novel catalytic activation mode,we developed and realized a relatively long-range activation strategy for free radicals in cyclopropyl alkenes,and identified the region of the 1,5-addition product in this reaction by two-dimensional spectroscopy.